U.S. patent number 8,940,581 [Application Number 13/298,140] was granted by the patent office on 2015-01-27 for packaged microelectronic devices and methods for manufacturing packaged microelectronic devices.
This patent grant is currently assigned to Micron Technology, Inc.. The grantee listed for this patent is Chin Hui Chong, David J. Corisis, Choon Kuan Lee. Invention is credited to Chin Hui Chong, David J. Corisis, Choon Kuan Lee.
United States Patent |
8,940,581 |
Lee , et al. |
January 27, 2015 |
Packaged microelectronic devices and methods for manufacturing
packaged microelectronic devices
Abstract
Packaged microelectronic devices and methods for manufacturing
packaged microelectronic devices are disclosed herein. In one
embodiment, a packaged microelectronic device can include a support
member, a first die attached to the support member, and a second
die attached to the first die in a stacked configuration. The
device can also include an attachment feature between the first and
second dies. The attachment feature can be composed of a dielectric
adhesive material. The attachment feature includes (a) a single,
unitary structure covering at least approximately all of the back
side of the second die, and (b) a plurality of interconnect
structures electrically coupled to internal active features of both
the first die and the second die.
Inventors: |
Lee; Choon Kuan (Singapore,
SG), Chong; Chin Hui (Singapore, SG),
Corisis; David J. (Nampa, ID) |
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Choon Kuan
Chong; Chin Hui
Corisis; David J. |
Singapore
Singapore
Nampa |
N/A
N/A
ID |
SG
SG
US |
|
|
Assignee: |
Micron Technology, Inc. (Boise,
ID)
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Family
ID: |
41399576 |
Appl.
No.: |
13/298,140 |
Filed: |
November 16, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20120187567 A1 |
Jul 26, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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12796740 |
Apr 3, 2012 |
8148807 |
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12136717 |
Jun 29, 2010 |
7745920 |
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Current U.S.
Class: |
438/108; 438/118;
438/668; 257/E21.599; 257/E23.011; 438/458 |
Current CPC
Class: |
H01L
25/50 (20130101); H01L 21/76898 (20130101); H01L
24/29 (20130101); H01L 23/3128 (20130101); H01L
23/481 (20130101); H01L 25/0657 (20130101); H01L
2224/48227 (20130101); H01L 2224/29005 (20130101); H01L
2224/48091 (20130101); H01L 2225/06572 (20130101); H01L
2924/10253 (20130101); H01L 2924/15311 (20130101); H01L
24/73 (20130101); H01L 2224/73207 (20130101); H01L
2225/0651 (20130101); H01L 2224/06181 (20130101); H01L
24/48 (20130101); H01L 2224/16145 (20130101); H01L
2224/32225 (20130101); H01L 2924/00014 (20130101); H01L
2224/73204 (20130101); H01L 2924/181 (20130101); H01L
2224/32145 (20130101); H01L 2924/15184 (20130101); H01L
2924/12042 (20130101); H01L 2225/06513 (20130101); H01L
2224/73265 (20130101); H01L 2225/06517 (20130101); H01L
2225/06565 (20130101); H01L 2924/01079 (20130101); H01L
2225/06541 (20130101); H01L 2224/48091 (20130101); H01L
2924/00014 (20130101); H01L 2224/73265 (20130101); H01L
2224/32225 (20130101); H01L 2224/48227 (20130101); H01L
2224/73265 (20130101); H01L 2224/32145 (20130101); H01L
2224/48227 (20130101); H01L 2924/00 (20130101); H01L
2224/73204 (20130101); H01L 2224/16145 (20130101); H01L
2224/32145 (20130101); H01L 2924/00 (20130101); H01L
2924/00 (20130101); H01L 2924/15311 (20130101); H01L
2224/73265 (20130101); H01L 2224/32225 (20130101); H01L
2224/48227 (20130101); H01L 2924/00 (20130101); H01L
2224/73265 (20130101); H01L 2224/32225 (20130101); H01L
2224/48227 (20130101); H01L 2924/00012 (20130101); H01L
2924/15311 (20130101); H01L 2224/73265 (20130101); H01L
2224/32225 (20130101); H01L 2224/48227 (20130101); H01L
2924/00012 (20130101); H01L 2924/10253 (20130101); H01L
2924/00 (20130101); H01L 2924/12042 (20130101); H01L
2924/00 (20130101); H01L 2224/73204 (20130101); H01L
2224/16145 (20130101); H01L 2224/32145 (20130101); H01L
2924/00 (20130101); H01L 2924/181 (20130101); H01L
2924/00012 (20130101); H01L 2924/00014 (20130101); H01L
2224/45099 (20130101); H01L 2924/00014 (20130101); H01L
2224/45015 (20130101); H01L 2924/207 (20130101) |
Current International
Class: |
H01L
21/58 (20060101) |
Field of
Search: |
;438/109,118,667,108,458
;257/E23.011,E21.599 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Todd, Michael et al., "Enabling Next-generation Stacked-die
Applications," Advanced Packaging, Apr. 2008,
<http://ap.pennnet.com/display.sub.--article/325751/36/ARTCL/none/none-
/1/Enabling-Next-generation-Stacked-die-Applications/>. cited by
applicant .
Todd, Michael, "Material systems enable high density packaging,"
Electronics Manufacturing Asia, Apr. 2008,
<http://www.emasiamag.com/article-3528-materialsystemsenablehighdensit-
ypackaging-Asia.html>. cited by applicant.
|
Primary Examiner: Smith; Zandra
Assistant Examiner: Thomas; Toniae
Attorney, Agent or Firm: Perkins Coie LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. application Ser. No.
12/796,740 filed Jun. 9, 2010, now U.S. Pat. No. 8,148,807, which
is a divisional of U.S. application Ser. No. 12/136,717 filed Jun.
10, 2008, now U.S. Pat. No. 7,745,920, each of which is
incorporated herein by reference in its entirety.
Claims
We claim:
1. A method for manufacturing stacked microelectronic devices, the
method comprising: placing an attachment structure on a back side
of a first microelectronic die, wherein the attachment structure
includes a plurality of openings at least partially aligned with
back side portions of electrically conductive through-substrate
interconnects in the first die, and wherein the attachment
structure further includes a plurality of conductive couplers
formed in at least a portion of the openings and electrically
coupled to corresponding through-substrate interconnects; after
placing the attachment structure on the back side of the first
microelectronic die, contacting the attachment structure with a
front side of a second microelectronic die; joining the back side
of the first die and the front side of the second die, wherein the
first die is physically and electrically connected with the second
die via the attachment structure; and attaching a back side of the
second die to a support member and electrically coupling the second
die to the support member before joining the first and second
dies.
2. The method of claim 1 wherein placing an attachment structure
comprises attaching a dielectric adhesive film having a plurality
of preformed openings to the back side of the first die.
3. The method of claim 2 wherein attaching a dielectric adhesive
film comprises attaching a single, unitary piece of adhesive film
that covers at least approximately all of the back side of the
first die.
4. The method of claim 1 wherein the second die is attached and
electrically coupled to the support member in a chip-on-board (COB)
configuration with a plurality of wire bonds connecting first
terminals at the front side of the second die with corresponding
contacts on the support member, and further wherein: joining the
back side of the first die and the front side of the second die
with the attachment structure includes (a) covering at least a
portion of the wire bonds with the attachment structure, and (b)
physically and electrically connecting the conductive couplers of
the attachment structure to corresponding second terminals at the
front side of the second die.
5. The method of claim 1 wherein the through-substrate
interconnects are first through-substrate interconnects, and
wherein the second die includes a plurality of second
through-substrate interconnects, and further wherein: joining the
back side of the first die and the front side of the second die
with the attachment structure includes physically and electrically
coupling first through-substrate interconnects with second
through-substrate interconnects via corresponding conductive
couplers of the attachment structure.
6. The method of claim 1 wherein the attachment structure is formed
at the back side of the first die and the conductive couplers are
electrically coupled to internal active features of the first die
before the first die is joined with the second die.
7. A method of processing a semiconductor substrate having a
plurality of microelectronic dies, the individual dies including
integrated circuitry and terminals electrically coupled to the
integrated circuitry, the method comprising: constructing a
plurality of electrically conductive through-substrate
interconnects extending at least partially through the
semiconductor substrate and in contact with corresponding
terminals; disposing a connection structure on a back side of the
semiconductor substrate, wherein the connection structure is a
single, unitary structure covering at least approximately the
entire back side of the semiconductor substrate and having a
plurality of preformed apertures at least partially aligned with
back side portions of the through-substrate interconnects; and
depositing conductive material into the apertures and forming a
plurality of conductive couplers in contact with back side portions
of the through-substrate interconnects.
8. The method of claim 7 wherein disposing a connection structure
on a back side of the semiconductor substrate comprises applying a
film-over-wire die attach film to the back side of the substrate,
the film having a size and shape at least approximately identical
to a size and shape of the semiconductor substrate.
9. The method of claim 7 wherein depositing conductive material
into the apertures comprises applying a first layer of Cu onto the
back side portions of the through-substrate interconnects, a second
layer of Ni over at least a portion of the first layer of Cu, and a
third layer of Au over at least a portion of the second layer of
Cu, and wherein the first, second, and third layers are applied
using a plating process.
10. The method of claim 7, further comprising removing material
from a back side of the semiconductor substrate to thin the
substrate after constructing the electrically conductive
through-substrate interconnects and before disposing the connection
structure on the back side of the semiconductor substrate.
11. A method of processing a semiconductor substrate having a
plurality of microelectronic dies, the individual dies including
integrated circuitry and terminals electrically coupled to the
integrated circuitry, the method comprising: constructing a
plurality of electrically conductive through-substrate
interconnects extending at least partially through the
semiconductor substrate and in contact with corresponding
terminals; disposing a connection structure on a back side of the
semiconductor substrate, the connection structure including a
single, unitary structure covering at least approximately the
entire back side of the semiconductor substrate and having a
plurality of preformed apertures at least partially aligned with
back side portions of the through-substrate interconnects;
depositing conductive material into the apertures and forming a
plurality of conductive couplers in contact with back side portions
of the through-substrate interconnects; and singulating the
semiconductor substrate after depositing the conductive material
into the apertures.
12. A method for manufacturing stacked microelectronic devices, the
method comprising: placing an attachment structure on a back side
of a first microelectronic die, wherein the attachment structure is
a dielectric adhesive film including a plurality of preformed
openings at least partially aligned with back side portions of
electrically conductive through-substrate interconnects in the
first die, and wherein the attachment structure further includes a
plurality of conductive couplers formed in at least a portion of
the openings and electrically coupled to corresponding
through-substrate interconnects; contacting the attachment
structure with a front side of a second microelectronic die; and
joining the back side of the first die and the front side of the
second die, wherein the first die is physically and electrically
connected with the second die via the attachment structure.
13. A method of processing a semiconductor substrate having a
plurality of microelectronic dies, the individual dies including
integrated circuitry and terminals electrically coupled to the
integrated circuitry, the method comprising: constructing a
plurality of electrically conductive through-substrate
interconnects extending at least partially through the
semiconductor substrate and in contact with corresponding
terminals; disposing a connection structure on a back side of the
semiconductor substrate, the connection structure comprising a
film-over-wire die attach film having a plurality of preformed
apertures at least partially aligned with back side portions of the
through-substrate interconnects, and wherein the die attach film
has a size and shape at least approximately identical to a size and
shape of the semiconductor substrate; and depositing conductive
material into the apertures and forming a plurality of conductive
couplers in contact with back side portions of the
through-substrate interconnects.
Description
TECHNICAL FIELD
The present disclosure is related to packaged microelectronic
devices and methods for manufacturing packaged microelectronic
devices.
BACKGROUND
Packaged microelectronic assemblies, such as memory chips and
microprocessor chips, typically include a microelectronic die
mounted to a substrate and encased in a plastic protective
covering. The die includes functional features, such as memory
cells, processor circuits, and interconnecting circuitry. The die
also typically includes bond pads electrically coupled to the
functional features. The bond pads are electrically connected to
pins or other types of terminals that extend outside the protective
covering for connecting the die to busses, circuits, or other
microelectronic assemblies. In one conventional arrangement, the
die is mounted (e.g., face up or face down) to a supporting
substrate (e.g., a printed circuit board), and the die bond pads
are electrically coupled to corresponding bond pads of the
substrate with wire bonds or metal bumps (e.g., solder balls or
other suitable connections). After encapsulation, additional metal
bumps can electrically connect the substrate to one or more
external devices. Accordingly, the substrate supports the die and
provides an electrical link between the die and the external
devices.
Die manufacturers have come under increasing pressure to reduce the
volume occupied by the dies and yet increase the capacity of the
resulting encapsulated assemblies. To meet these demands, die
manufacturers often stack multiple dies on top of each other to
increase the capacity or performance of the device within the
limited surface area on the circuit board or other element to which
the dies are mounted.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a partially schematic illustration of a representative
microelectronic workpiece carrying microelectronic dies configured
in accordance with embodiments of the disclosure.
FIG. 1B is a schematic illustration of a microelectronic die
singulated from the workpiece shown in FIG. 1A.
FIG. 2 is a schematic, side cross-sectional view of a packaged
microelectronic device configured in accordance with an embodiment
of the disclosure.
FIGS. 3A-3G illustrate various stages of a method for manufacturing
a plurality of microelectronic devices having attachment features
in accordance with an embodiment of the disclosure.
FIGS. 4A-4C illustrate various stages of a method for manufacturing
a plurality of microelectronic devices in accordance with another
embodiment of the disclosure.
FIG. 5 is a schematic, side cross-sectional view of a packaged
microelectronic device configured in accordance with still another
embodiment of the disclosure.
FIG. 6 is a schematic illustration of a system that can include one
or more microelectronic devices configured in accordance with
embodiments of the disclosure.
DETAILED DESCRIPTION
Specific details of several embodiments of the disclosure are
described below with reference to packaged microelectronic devices
and methods for manufacturing such devices. The microelectronic
devices described below include two microelectronic dies attached
to each other in a stacked configuration, but in other embodiments
the microelectronic devices can have three or more stacked
microelectronic dies electrically coupled to each other and, in
some cases, a support member. The microelectronic devices can
include, for example, micromechanical components, data storage
elements, optics, read/write components, or other features. The
microelectronic dies can be SRAM, DRAM (e.g., DDR-SDRAM), flash
memory (e.g., NAND flash memory), processors, imagers, and other
types of devices. The term "interconnect" may encompass various
types of conductive structures that extend at least partially
through a substrate of a microelectronic die or another component
and electrically couple together conductive contacts located at
opposing ends of the interconnect. Substrates can be semiconductive
pieces (e.g., doped silicon wafers, gallium arsenide wafers, or
other semiconductor wafers), nonconductive pieces (e.g., various
ceramic substrates), or conductive pieces. Moreover, several other
embodiments of the disclosure can have configurations, components,
or procedures different than those described in this section. A
person of ordinary skill in the art, therefore, will accordingly
understand that the disclosure may have other embodiments with
additional elements, or the disclosure may have other embodiments
without several of the elements shown and described below with
reference to FIGS. 2-6.
FIG. 1A is a microelectronic workpiece 100 in the form of a
semiconductor wafer 110 that includes multiple microelectronic dies
120. At least some of the processes described below may be
conducted on the microelectronic workpiece 100 at the wafer level,
and other processes may be conducted on the individual
microelectronic dies 120 of the microelectronic workpiece 100 after
the dies 120 have been singulated from the larger wafer 110.
Accordingly, unless otherwise noted, structures and methods
described below in the context of a microelectronic workpiece can
apply to the wafer 110, the dies 120 that are formed from the wafer
110, and/or an assembly of one or more dies 120 in a stacked-die
configuration or attached to a support member. FIG. 1B is a
schematic illustration of an individual die 120 after it has been
singulated from the wafer 110 shown in FIG. 1A. The die 120 can
include operable microelectronic structures, optionally encased
within a protective encapsulant. The die 120 can be electrically
connected to external structural devices by pins, bond pads, solder
balls, redistribution structures, and/or other conductive
structures.
FIG. 2 is a schematic, side cross-sectional view of a
microelectronic device 200 configured in accordance with an
embodiment of the disclosure. The device 200 includes a first
microelectronic die 220 attached to a support member 202, and a
second microelectronic die 240 attached to the first die 220 in a
stacked configuration. The device 200 also includes an attachment
feature or structure 260 between the first die 220 and the second
die 240. The attachment feature 260 is configured to provide both a
mechanical and an electrical connection between the first die 220
and the second die 240, as described in greater detail below.
The support member 202 can include an interposer substrate, a
printed circuit board, a lead frame, or another suitable support
member. The support member 202 can be composed of an organic
material, a ceramic material, or another suitable dielectric
material. The support member 202 can include a first side 204 and a
second side 206 opposite the first side 204. In the illustrated
embodiment, the support member 202 is an interposing device that
provides an array of ball-pads for coupling very small contacts on
the first and/or second dies 220 and 240 to another type of device
(not shown). The support member 202, for example, includes an array
of support member terminals 208 at the first side 204, an array of
contact pads 210 (e.g., ball-pads) at the second side 206, and a
trace 212 or other type of conductive line between each support
member terminal 208 and one or more corresponding contact pads 210.
The contact pads 210 are arranged in an array for surface mounting
the device 200 to a board or module of another device (not shown).
A plurality of electrical couplers 216 (e.g., solder balls or
conductive bumps) can be attached to corresponding contact pads
210. In other embodiments, the support member 202 can include
different features and/or the features can have a different
arrangement.
The first microelectronic die 220 can be a semiconductor die or
other type of microelectronic die. The first die 220, for example,
can be a processor, a memory device (e.g., a DRAM or flash memory
device), a sensor, a filter, or other type of microelectronic
device. The first die 220 includes an active or front side 222 and
a back side 224 opposite the active side 222. The active or front
side 222 generally refers to the side of the first die 220 that is
accessed during formation of the active elements of the first die
220. The first die 220 also includes integrated circuitry 226
(shown schematically) and a plurality of terminals 228 (e.g.,
bond-pads) arranged in an array at the active side 222 and
electrically coupled to the integrated circuitry 226. The terminals
228 accordingly provide external contacts to provide source
voltages, ground voltages, and signals to the integrated circuitry
226 of the first die 220. The terminals 228, however, are typically
so small that it is difficult to attach the terminals 228 directly
to contacts on other devices in a cost-effective manner. The first
die 220 accordingly includes a redistribution structure or
redistribution layer (RDL) 230 at the active side 222 to
redistribute the signals from the terminals 228 to a larger array
of contacts.
The redistribution structure 230, for example, can include one or
more dielectric layers 232, a plurality of peripheral contacts 234
at or proximate to a perimeter portion of the front or active side
222, and a plurality of traces or other conductive lines (not
shown) coupling at least a portion of the terminals 228 to
corresponding peripheral contacts 234. The peripheral contacts 234
can be used to electrically couple the first die 220 to the support
member terminals 208 of the support member 202 (e.g., using a
chip-on-board (COB) configuration) with a plurality of wire bonds
236 or other types of connectors extending between the peripheral
contacts 234 and corresponding support member terminals 208. In
other embodiments, the redistribution structure 230 can include
different features and/or the features can have a different
arrangement. In still other embodiments, the first die 220 may not
include the redistribution structure 230. In several embodiments,
the device 200 can further include an adhesive material 238, such
as an adhesive film, epoxy, tape, paste, or other suitable material
disposed between the first die 220 and the support member 202 to
help attach the first die 220 to the support member 202.
The second microelectronic die 240 stacked on the first die 220 can
be a semiconductor die or other type of microelectronic die. The
second die 240, for example, can be a processor, a memory device
(e.g., a DRAM or flash memory device), an imager, a sensor, a
filter, or other type of microelectronic device. The second die 240
includes an active or front side 242 and a back side 244 opposite
the active side 242. The second die 240 also includes integrated
circuitry 246 (shown schematically) and electrical connectors 248
(only one is shown) electrically coupled to the integrated
circuitry 246.
The electrical connectors 248 provide a small array of back side
contacts within the footprint of the second die 240. The individual
connectors 248, for example, can include a terminal or bond site
250 (e.g., a bond-pad) and an interconnect 252 coupled to the
terminal 250. In the embodiment illustrated in FIG. 2, the terminal
250 is at the front side 242 of the second die 240 and the
interconnect 252 is a through-substrate or through-wafer
interconnect that extends completely through the second die 240 to
electrically couple the terminal 250 to corresponding features at
the back side 244. In other embodiments, however, the terminal 250
can be an internal feature that is embedded at an intermediate
depth within the second die 240 and coupled to a corresponding
interconnect 252 that extends through only a portion of the second
die 240. In other embodiments, the first die 220 and/or the second
die 240 can have different features to perform different
functions.
The device 200 can also include an encapsulant, shell, or cap 290
formed or otherwise deposited over the first and second dies 220
and 240 and at least a portion of the support member 202. The
encapsulant 290 enhances the integrity of the device 200 and
protects the first and second dies 220 and 240 and the physical and
electrical connections between the dies 220 and 240 and the support
member 202 from moisture, chemicals, and other contaminants.
As mentioned previously, the device 200 further includes the
attachment feature 260 between the first die 220 and the second die
240 to physically and electrically attach the first and second dies
together. In several embodiments, the attachment feature 260 can
comprise a film-over-wire (FOW) die attach film applied over
approximately the entire back side 244 of the second die 240. The
attachment feature 260 is configured to protect the wire bonds 236,
the redistribution structure 230, and other delicate front side
components of the first die 220 from being damaged when the second
die 240 is attached to the first die 220 using a die attachment
process. The attachment feature 260 further includes an
interconnect structure or conductive coupler 272 extending at least
partially through the attachment feature 260 and coupled to the
interconnect 252 of the second die 240. The interconnect structure
272 is configured to electrically couple the interconnect 252 of
the second die 240 to the terminals 228 of the first die 220. The
attachment feature 260 and its respective components are described
in greater detail below with reference to FIGS. 3E-3G.
Several embodiments of the microelectronic device 200 including the
attachment feature 260 may provide improved package reliability and
robustness as compared with conventional stacked devices.
Conventional devices, for example, typically include an underfill
material in a gap between an upper die and a lower die of the
stacked device. The underfill material is generally dispensed into
the gap by injecting the underfill material along one or two sides
of the device, and the material is drawn into the gap by capillary
effects. One potential drawback with this approach, however, is
that it may result in a vulnerable mechanical connection between
the two dies. For example, when the underfill material flows into
the gap between the components, air bubbles, air pockets, and/or
voids may form within the underfill material. During subsequent
high temperature processes, the air trapped in these regions may
expand and force the dies away from each other, damaging the
mechanical and/or electrical connections between these components.
This in turn often leads to failure or malfunction of such
devices.
Unlike conventional stacked devices (which typically include
underfill material between the upper and lower dies), several
embodiments of the attachment feature 260 of the device 200
significantly reduce or eliminate the chances for air bubbles, air
pockets, and/or voids to form in the gap between the two dies. For
example, when the attachment feature 260 is a preformed film or
tape, the quality control can ensure the film or tape is at least
substantially void free within the material of the film.
Eliminating the underfill material between the first and second
dies 220 and 240 is expected to provide a more robust and reliable
connection between the components, thereby reducing and/or
eliminating the tendency for the mechanical and/or electrical
connections in the device 200 to fail.
In the embodiment illustrated in FIG. 2, formation of the device
200 including the attachment feature 260 between the first and
second dies 220 and 240 is complete. FIGS. 3A-4C described below
illustrate various embodiments of methods for forming attachment
features on microelectronic dies. Although the following
description illustrates only a single interconnect adjacent to a
portion of the attachment feature, it will be appreciated that (a)
a plurality of interconnects are constructed simultaneously through
a plurality of dies on a wafer, and (b) the attachment feature is
fabricated across all or a substantial portion of a workpiece.
FIGS. 3A-3G illustrate various stages of a method for forming one
embodiment of the attachment feature 260 of FIG. 2. FIG. 3A, more
specifically, is a schematic, side cross-sectional view of a
portion of a microelectronic workpiece 300 at an early stage of
this process after constructing a substantial portion of an
embodiment of the interconnect 252 (FIG. 2), but before
constructing the attachment feature 260. The workpiece 300 includes
a semiconductor substrate 302 having a front or active side 304, a
back side 306, and a plurality of microelectronic dies (e.g., a
plurality of second dies 240 of FIG. 2) formed on and/or in the
substrate 302. The workpiece 300 can include several features
generally similar to the workpiece 100 described above with
reference to FIG. 1A. The substrate 302, for example, can be a
semiconductor wafer with the dies arranged in a die pattern on the
wafer. In other embodiments, however, the workpiece 300 can have a
different arrangement and/or include different features.
The workpiece 300 has first and second dielectric layers 310 and
312 over at least a portion of the front side 304 of the substrate
302 to protect the substrate 302 and the terminals 250. The
dielectric layers 310 and 312 and/or one or more of the subsequent
dielectric layers can be parylene, low temperature chemical vapor
deposition (CVD) materials, such as silicon nitride
(Si.sub.3Ni.sub.4), silicon oxide (SiO.sub.2), and/or other
suitable dielectric materials. The foregoing list of dielectric
materials is not exhaustive. The dielectric layers 310 and 312 are
not generally composed of the same material as each other, but
these layers may be composed of the same material. In addition, one
or both of the dielectric layers 310 and 312 may be omitted and/or
additional layers may be included.
The workpiece 300 also includes a plurality of vias or apertures
320 (only one is shown) formed through at least part of the
substrate 302 using etching, laser drilling, or other suitable
techniques. The illustrated vias 320 are blind vias that extend
only partially through the substrate 302 or are otherwise closed at
one end. In other embodiments, however, the vias 320 can extend
entirely through the workpiece 300 and/or the substrate 302.
Further details of representative methods for forming vias 320 are
disclosed in U.S. Pat. No. 7,271,482, issued Sep. 18, 2007, and
incorporated herein by reference in its entirety.
The via 320 is generally lined with another dielectric layer and
one or more conductive layers (shown collectively as liner 314).
The embodiment of the liner 314 is shown schematically as a single
layer, but in many embodiments the liner 314 has a number of
different dielectric and conductive materials. The dielectric
layer(s) of the liner 314 electrically insulate the components in
the substrate 302 from the interconnect that is subsequently formed
in the via 320. The dielectric layer(s) of the liner 314 can
include materials similar to those of the dielectric layers 310 and
312 described above. The conductive layer(s) of the liner 314 can
include tantalum (Ta), tungsten (W), copper (Cu), nickel (Ni),
and/or other suitable conductive materials. After lining the via
320, a vent hole 325 may be formed in the substrate 302 to extend
from a bottom portion of each via 320 to the back side 306 of the
substrate 302.
Referring next to FIG. 3B, a conductive fill material 322 is
deposited into the via 320 to form the interconnect 252. The fill
material 322 can include Cu, Ni, silver (Ag), gold (Au), solder, a
conductive polymer, or other suitable materials or alloys of
materials having the desired fill properties. The vent hole 325
allows trapped air, gases, or volatile solvents to escape from the
larger vias 320 when filling the vias with the conductive fill
material 322. The vent hole 325 is an optional structure that may
be omitted in several embodiments.
Referring next to FIG. 3C, the substrate 302 is thinned from a
first or initial thickness T.sub.1 (shown in broken lines) to a
second or final thickness T.sub.2 by removing material from the
back side 306 of the substrate 302. In the illustrated embodiment,
a back side portion 326 of each interconnect 252 is at least
partially exposed after removing material from the back side 306.
In one embodiment, the first thickness T.sub.1 of the substrate 302
is approximately 600 to 800 microns, and the second thickness
T.sub.2 is approximately 50 to 100 microns. The initial and/or
final thicknesses can be different in other embodiments. The back
side 306 of the substrate 302 can be thinned using
chemical-mechanical planarization (CMP) processes, dry etching
processes, chemical etching processes, chemical polishing, grinding
procedures, or other suitable processes.
Referring to FIG. 3D, the back side 306 of the substrate 302 is
etched back (e.g., using a dry etch or another suitable etching
process) to further expose the back side portion 326 of the
interconnect 252, thus forming a conductive "post" or projection
330. In other embodiments, other suitable processes in addition to,
or in lieu of, the etching process can be used to offset the back
side 306 of the substrate 302 from the end of the interconnect 252
to form the post 330. In one embodiment, the post 330 has a height
of approximately 10-30 microns above the back side 306 of the
substrate 302. In other embodiments, however, the post 330 may have
a different height relative to the back side 306.
Referring next to FIG. 3E, after forming the post 330, a film or
layer 332 is deposited onto the back side 306 to form a portion of
the attachment feature 260 (FIG. 2). In one embodiment, the film
material can be formed separately from the workpiece 300 and then
applied onto desired portions of the workpiece 300 to form the film
or layer 332. For example, a wafer-sized portion of film material
(i.e., a portion of film material having a size and shape generally
corresponding to that of the substrate 302) can be disposed over
approximately the entire back side 306. As mentioned previously,
for example, the film 332 can be a FOW die attach film composed of
a dielectric adhesive material (e.g., an epoxy resin) or another
suitable material having the desired properties. Further details
regarding suitable FOW die attach films are provided in U.S. Pat.
No. 6,388,313, which is incorporated herein by reference in its
entirety. Alternatively, the film 332 can have a different size
and/or configuration. In one embodiment, for example, the film 332
may be disposed over only a portion of the back side 306 of the
substrate 302.
The film 332 includes a plurality of preformed openings or
apertures 334 (only one is shown) sized and positioned to expose at
least a portion of the corresponding posts 330. In the illustrated
embodiment, for example, the opening 334 has a diameter or
cross-sectional dimension D greater than a diameter or
cross-sectional dimension of the corresponding post 330. The
diameter D of the opening 334 can be sized such that both the back
side portion 326 of the corresponding interconnect 252 and at least
a portion of the back side 306 of the substrate 302 adjacent to the
interconnect 252 are exposed. In other embodiments, however, the
openings 334 may have a different size and/or arrangement.
As mentioned above, the openings 334 are preformed openings formed
in the film 332 before the film material is applied onto the back
side 306 of the substrate 302. The openings 334, for example, can
be formed in the film 332 using a punching or stamping process, an
etching process, or another suitable process. In other embodiments,
the openings 334 can be preformed in the film 332 using other
suitable techniques. In still other embodiments, the openings 334
may be formed in the film 332 after the film 332 is applied onto
the back side 306 (e.g., using an etching process). After applying
the film 332 to the back side 306, the film material can be cured
(e.g., using a heat process) after application.
Referring next to FIG. 3F, one or more conductive layers (shown
collectively as layer 340) are deposited into the opening 334 and
in electrical contact with the post 330 to form the interconnect
structures or conductive couplers 272 (only one is shown). The
embodiment of the conductive layer 340 is shown schematically as a
single layer, but in many embodiments the layer 340 has a number of
different conductive materials. Furthermore, although the layer 340
is shown at least approximately completely filling the opening 334,
in other embodiments the layer 340 may only fill a portion of the
opening 334. The conductive layer 340 can include Cu, Ni, Au,
palladium, Ag, solder, a conductive polymer, or other suitable
materials or alloys of materials having the desired conductive
properties. In one particular embodiment, for example, the layer
340 can include a tri-layer arrangement of conductive materials.
The three layers include a first layer of Cu plated onto the post
330, a second layer of Ni plated onto the first layer, and a third
layer of Au plated onto the second layer. In another particular
embodiment having a tri-layer arrangement, the three layers can
include Ni, Au, and palladium. In still another embodiment, the
layer 340 may include a single layer of Cu in electrical contact
with the post 330. In yet other embodiments, the layer 340 can
include other suitable material(s).
FIG. 3G is a bottom plan view of the portion of the workpiece 300
shown in FIG. 3F. Referring to FIGS. 3F and 3G together, an outer
surface 341 of the interconnect structures 272 is approximately
co-planar or flush with a bottom surface 262 of the attachment
feature 260. The interconnect structures 272 accordingly provide an
external electrical connection to other electronic devices at the
bottom surface 262 of the attachment feature 260. The generally
planar surface across the entire lower portion of the workpiece 300
is expected to enable the attachment feature 260 to form reliable
and robust mechanical and electrical connections with a
corresponding device (e.g., the first die 220 of FIG. 2) in a
stacked configuration without requiring an underfill material or
additional electrical connectors. In the embodiment shown in FIG.
3G, the interconnect structures 272 are arranged in a generally
linear arrangement and configured to transmit signals to and/or
from one or more external devices (not shown). It will be
appreciated, however, that the interconnect structures 272 can have
a variety of different patterns or arrangements (e.g., a ball-grid
array) depending upon the particular arrangement of electrical
contacts at the back side 306 of the substrate 302.
In other embodiments, the outer surface 341 of the conductive layer
340 may not be co-planar with the bottom surface 262 of the
attachment feature 260. In one embodiment, for example, the outer
surface 341 may be recessed relative to the bottom surface 262. In
this arrangement, one or more suitable electrical connectors (e.g.,
a gold bump, solder ball, etc.--not shown in FIGS. 3F and 3G) may
be used to electrically and physically couple the interconnect
structure 272 to the respective contacts on the corresponding
microelectronic device (not shown). In still another embodiment,
the outer surface 341 may project outwardly a desired distance
beyond the bottom surface 262 of the attachment feature 260.
After forming the attachment feature 260 at the back side 306 of
the substrate 302, the workpiece 300 can be singulated to form a
plurality of individual microelectronic dies (e.g., the second die
240 of FIG. 2). The attachment feature 260 at the back side 306 of
the individual dies can be used to attach the dies to corresponding
dies (e.g., the first die 220 of FIG. 2) in a stacked
configuration.
FIGS. 4A-4C are schematic, side cross-sectional views illustrating
various stages of a method for forming the second die 240 and the
attachment feature 260 of FIG. 2 in accordance with another
embodiment of the disclosure. This method begins with the substrate
302, the first dielectric layer 310, the second dielectric layer
312, and the terminal 250. The initial stages of this method are at
least generally similar to the steps described above with reference
to FIGS. 3A, and as such FIG. 4A shows a workpiece configuration
similar to that illustrated in FIG. 3A. The process shown in FIGS.
4A-4C, however, differs from the method described above with
respect to FIGS. 3A-3G in that a hole or via is formed from the
back side 306 of the substrate 302 instead of the front side 304.
Before forming the blind hole, the substrate 302 can be thinned by
removing material from the back side 306 of the substrate 302 until
the substrate 302 has the desired thickness T.sub.2 (e.g.,
approximately 50-100 microns). The substrate 302 can be thinned
using processes similar to those described above with reference to
FIG. 3C (e.g., CMP processes, dry etching processes, etc.).
FIG. 4B is a schematic, side cross-sectional view of the substrate
302 after a blind hole or via 420 has been formed through the
substrate 302 and the first dielectric layer 310 and in alignment
with a corresponding terminal 250. The hole 420 is formed by
patterning the back side 306 of the substrate 302 and etching
through the substrate 302 from the back side 306. The hole 420 can
be etched using one or more etching processes that selectively
remove material from the substrate 302 and the first dielectric
layer 310 compared to the terminal 250. The hole 420 can
alternatively be formed using a laser in addition to or in lieu of
etching. If a laser is used to form all or a portion of the hole
420, it is typically cleaned using chemical cleaning agents to
remove slag or other contaminants.
After forming the hole 420, the hole 420 is generally lined with
another dielectric layer and one or more conductive layers (shown
collectively as liner 422). As with the liner 314 of FIG. 3A, the
liner 422 is shown schematically as a single layer, but in many
embodiments the liner 422 has a number of different dielectric and
conductive materials. The liner 422 can include materials generally
similar to the liner 314 described above. Referring next to FIG.
4C, a conductive fill material 424 is deposited into the hole 420
to form the interconnect 252. The fill material 424 can be
generally similar to the fill material 322 described above with
reference to FIG. 3B. The fill material 424 can be deposited into
the hole 420 using a solder wave process, electroplating,
electroless plating, or other suitable methods. After the fill
material 424 has been deposited to form the interconnect 252, the
substrate 302 can undergo additional processing steps that are at
least generally similar to those described above with reference to
FIGS. 3D-3G to construct an attachment feature at the back side 306
of the substrate 302.
FIG. 5 is a schematic, side cross-sectional view of a packaged
microelectronic device 500 configured in accordance with an
embodiment of the disclosure. The device 500 can include several
features generally similar to the device 200 of FIG. 2. For
example, the device 500 includes plurality of microelectronic dies
540 (individually identified as a first microelectronic die 540a
and a second microelectronic die 540b) interconnected in a
stacked-die arrangement with the attachment feature 260. The first
die 540a is attached and electrically coupled to a support member
502. The device 500 differs from the device 200 described above in
that the lower or bottom die in the stacked arrangement (i.e., the
first die 540a) has a different configuration than the lower or
bottom die (i.e., the first die 220) of the device 200 shown in
FIG. 2. In this embodiment, for example, the first and second dies
540a and 540b are at least approximately identical to each
other.
The first and second dies 540a and 540b can have many components
generally similar to the second microelectronic die 240 discussed
above and illustrated in FIG. 2. For example, the first and second
dies 540a and 540b can include integrated circuitry 546 and
connectors 548 electrically coupled to the integrated circuitry
546. Each connector 548 can include a terminal or bond site 550
(e.g., a bond pad) and an interconnect 552 coupled to the terminal
550. The interconnects 552 are through-substrate or through-wafer
interconnects that extend completely through the respective dies to
couple the terminal 550 to corresponding features at back sides
544a and 544b of the first and second dies 540a and 540b,
respectively. The attachment feature 260 provides both a physical
and an electrical connection between the first and second dies 540a
and 540b. For example, the interconnect structure 272 of the
attachment feature 260 is coupled to a back side portion of the
interconnect 552 of the second or upper die 540b, and electrically
couples the second die 540b to the terminal 550 at a front or
active side 542a of the first die 540a.
The support member 502 can be generally similar to the support
member 202 described above with reference to FIG. 2. For example,
the support member 502 includes a first side 504 and a second side
506 opposite the first side 504. The support member 502 also
includes an array of support member terminals 508 at the first side
504, an array of contact pads 510 at the second side 506, and a
trace 512 or other type of conductive line between each support
member terminal 508 and one or more corresponding contact pads 510.
The contact pads 510 are arranged in an array for surface mounting
the device 500 to a board or module of another device (not shown).
A plurality of electrical couplers 516 (e.g., solder balls or
conductive bumps) can be attached to corresponding contact pads
510. The device 500 can also include an encapsulant, shell, or cap
590 formed or otherwise deposited over the first and second dies
540a and 540b and at least a portion of the support member 502.
The microelectronic devices 200 and 500 or any one of the
microelectronic devices formed using the methods described above
with reference to FIGS. 1A-5 can be incorporated into any of a
myriad of larger and/or more complex systems 600, a representative
one of which is shown schematically in FIG. 6. The system 600 can
include a processor 602, a memory 604 (e.g., SRAM, DRAM, DDR-SDRAM,
flash memory, such as NAND flash memory or other types of flash
memory, and/or other suitable memory devices), input/output devices
606, and/or other subsystems or components 608. Microelectronic
devices and/or microfeature workpieces (e.g., in the form of
microfeature dies and/or combinations of microfeature dies) may be
included in any of the components shown in FIG. 6. The resulting
system 600 can perform any of a wide variety of computing,
processing, storage, sensor, imagers, and/or other functions.
Accordingly, representative systems 600 include, without
limitation, computers and/or other data processors, for example,
desktop computers, laptop computers, Internet appliances, hand-held
devices (e.g., palm-top computers, wearable computers, cellular or
mobile phones, personal digital assistants), multi-processor
systems, processor-based or programmable consumer electronics,
network computers, and mini-computers. Other representative systems
600 include cameras, light or other radiation sensors, servers and
associated server subsystems, display devices, and/or memory
devices. In such systems, individual dies can include imager
arrays, such as a CMOS imager. Components of the system 600 may be
housed in a single unit or distributed over multiple,
interconnected units, e.g., through a communications network.
Components can accordingly include local and/or remote memory
storage devices and any of a wide variety of computer-readable
media.
From the foregoing, it will be appreciated that specific
embodiments of the disclosure have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the spirit and scope of the disclosure.
For example, structures and/or processes described in the context
of particular embodiments may be combined or eliminated in other
embodiments. In particular, the attachment features described above
with reference to particular embodiments can include one or more
additional features or components, or one or more of the features
described above can be omitted. Further, the connections between
the attachment feature, the interconnects, and other devices (e.g.,
bond pads, conductive couplers, and/or external devices) can have
arrangements different than those described above. Moreover, while
advantages associated with certain embodiments of the disclosure
have been described in the context of these embodiments, other
embodiments may also exhibit such advantages, and not all
embodiments need necessarily exhibit such advantages to fall within
the scope of the disclosure. Accordingly, embodiments of the
disclosure are not limited except as by the appended claims.
* * * * *
References